A cycloidal gearbox is a modern, compact transmission element providing a possibility of achieving big gear ratios. In comparison with other kinds of transmission gears the cycloidal gearbox has a high effectivity, high torque overload capacity, long service life, low noisiness, low weight and small built-in dimensions. A disadvantage of all prior art cycloidal gearboxes consists in that they have a realtively big axial dimension. This dimension is a consequence of their construction, where on the back side of a gearbox an input shaft is arranged, while on the front side an output shaft is arranged with the necessity of seating of the input shaft, and if need be even a seating of the output shaft in bearings, what is evident e.g. from DE PS No. 28 35 973, which is incorporated into this description as a reference. Such an arrangement of a gearbox does not allow its direct coupling, without a seating of its own, to a driven, ev. driving unit.